Lily Collins worked with nutritionist for months after To the Bone wrapped

Lily Collins consulted with a nutritionist for several months after she made movie To The Bone.

Based on director Marti Noxon's own experience with eating disorders, the new film focusing on Ellen, a young anorexic woman played by Lily, who is shepherded through various recovery programs, only to find herself several pounds lighter every time.

While Lily was willing to transform her figure for the role, Marti and the producers were very mindful of her personal history with anorexia and bulimia as a teenager and coached her through the project with the help of health professionals.

"We had her work with a nutritionist, who actually worked with her throughout the entire process and for months after who, as she was gaining the weight back, was checking in with her all of the time," Marti told People.com. "We never asked her to lose a certain amount of weight."

Lily, 28, has previously spoken about why she chose to lose some weight for the drama, explaining that the process helped her to fully embrace the role. The Rules Don't Apply actress, who is the daughter of music icon Phil Collins, never had a weight loss "goal" set in the lead-up to the shoot.

"It's something that I decided to do as an actor for a role. You lose weight, you gain weight, you change your hair color. There's so many different things that you can physically change for a character," she shared with Access Hollywood previously.

While Marti and her colleagues utilized special effects, make-up and prosthetics to make Lily appear very thin and gaunt, the star's decision to lose weight has been condemned by some health organizations including Project Heal, a nonprofit which aids those with eating disorders.

Members of Project Heal did consult on aspects of the film, but still advise against such behavior.

"We in no way intend to endorse the idea that people with anorexia nervosa can lose weight safely. This was a creative decision on the filmmakers' part, and filming was completed before Project Heal got involved in the film," organizers wrote in a statement.